Atrial Capture Research Articles

GW24-e0798 Clinical observation of ACapTMcomfirm in Zephyr5826 pacemaker

ObjectivesTo observe the atrial capture management in Zephyr5826 pacemaker. By calculating the open rate of ACapTMcomfirm in different circumstances and comparing atrial thresholds measured automatically and manually, we evaluate its...

Anteroseptal basal right ventricular entrainment is simple and superior to apical entrainment in identifying mechanism of supraventricular tachycardia

Differentiation between atrioventricular nodal reentry tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) can be sometimes challenging. Apical right ventricular (RV) entrainment can help in differentiation; however, it has some fallacies. We thought to compare the accuracy of anteroseptal basal RV entrainment to RV apical entrainment in identifying the mechanism of supraventricular tachycardia (SVT). Forty-two consecutive patients with SVT who underwent catheter ablation were prospectively studied. Apical RV entrainment was performed initially followed by basal entrainment from the anteroseptal basal RV avoiding His or atrial capture. Postpacing interval (PPI), PPI-tachycardia cycle length (TCL), corrected PPI-TCL, and stimulus-atrial minus ventricular-atrial (VA) intervals were measured. Entrainment was achieved from both sites of RV in 34 patients (ten men; mean age 42 ± 15 years), 20 with typical AVNRT, 1 with atypical AVNRT, and 13 with AVRT (eight left sided, four right sided, and one septal accessory pathways). PPI-TCL, corrected PPI (cPPI)-TCL, and stimulus-atrial-VA intervals were significantly longer with basal entrainment in AVNRT (171 ± 30 vs. 153 ± 22 ms (p = 0.003), 148 ± 21 vs. 131 ± 20 ms (p = 0.002), and 145 ± 17 vs. 136 ± 15 ms (p = 0.005), respectively). Receiver-operating characteristic curves showed higher AUC for the above parameters with basal entrainment compared to apical entrainment. Cutoff values of basal PPI-TCL of >110 ms and cPPI-TCL of >95 ms had better sensitivities (100 % for both vs. 95 and 90 %, respectively, for apical values) and specificities (85 and 92 % vs. 77 and 92 %, respectively) for diagnosis of AVNRT. Basal RV entrainment from the anteroseptal basal RV is a simple maneuver that is superior to apical ventricular entrainment in identifying the mechanism of SVT.

Atrial mechanical and electrical dysfunction in patient with Emery-Dreifuss muscular dystrophy reason of change in electrotherapeutical approach: frequent result of rare disease

We present a case of a 35 year-old male patient with Emery-Dreifuss muscular dystrophy diagnosed in the age of 12 who was assigned to dual chamber pacing system due to bradycardia primarily recognised as sinus node insufficiency with the atrio-ventricular nodal rhythm. During the procedure permanent electrical atrial stand-still without atrial capture were detected and the mode of stimulation was change to VVIR.

Effect of Atrial Capture Beats on the Subsequent Cycle During Slow Common Atrioventricular Nodal Reentry Tachycardia

Effect of Atrial Capture Beats on the Subsequent Cycle During Slow Common Atrioventricular Nodal Reentry Tachycardia

Termination of peri-mitral atrial flutter involving coronary sinus by single extrastimulus with non-global atrial capture

A 62-year-old man with dilated cardiomyopathy was admitted for catheter ablation of recurrent uncommon atrial tachycardia (AT). The baseline tachycardia cycle length was 260 ms. Counter-clockwise peri-mitral atrial flutter (PMAFL) involving the coronary sinus (CS) was diagnosed using entrainment and three-dimensional electroanatomical …

Clinical evaluation of pacemaker automatic capture management and atrioventricular interval extension algorithm

The present study was to assess the accuracy of automatic atrial and ventricular capture management (ACM and VCM) in determining pacing threshold and the performance of a second-generation automatic atrioventricular (AV) interval extension algorithm for reducing unnecessary ventricular pacing. A total of 398 patients at 32 centres who received an EnPulse dual-chamber pacing/dual-chamber adaptive rate pacing pacemaker (Medtronic, Minneapolis, MN, USA) were enrolled. The last amplitude thresholds as measured by ACM and VCM prior to the 6-month follow-up were compared with manually measured thresholds. Device diagnostics were used to evaluate ACM and VCM and the percentage of ventricular pacing with and without the AV extension algorithm. Modelling was performed to assess longevity gains relating to the use of automaticity features. Atrial and ventricular capture management performed accurately and reliably provided complete capture management in 97% of studied patients. The AV interval extension algorithm reduced the median per cent of right ventricular pacing in patients with sinus node dysfunction from 99.7 to 1.5% at 6-month follow-up and in patients with intermittent AV block (excluding persistent 3° AV block) from 99.9 to 50.2%. On the basis of validated modelling, estimated device longevity could potentially be extended by 1.9 years through the use of the capture management and AV interval extension features. Both ACM and VCM features reliably measured thresholds in nearly all patients; the AV extension algorithm significantly reduced ventricular pacing; and the use of pacemaker automaticity features potentially extends device longevity.

Is This a Good Target Site for Ablation of an Atrial Tachycardia?

This article describes the case of a 68-year-old woman who was referred for atrial tachycardia following a catheter ablation procedure. The tachycardia terminated despite the fact that the pacing stimulus did not result in atrial capture. This finding is very specific for identifying a critical site in a reentry circuit.

Unipolar and Bipolar Electrogram Characteristics Predict Exit Block during Pulmonary Vein Antral Isolation

The usefulness of unipolar electrograms (EGMs) has been reported in assessing lesion transmurality and conduction block along ablation lines. It is unknown whether unipolar and bipolar EGM characteristics predict exit block during pulmonary vein isolation (PVI) procedures. Twenty patients (63 ± 7 years; 14 males [70%]) undergoing PVI with a circular mapping catheter (CMC) placed outside each PV ostium were retrospectively studied. After entrance block was achieved, pacing at each bipole around the CMC was performed to assess for absence of atrial capture (exit block). Bipolar EGMs recorded before pacing were examined for voltage, duration, fractionation, and monophasic morphology. Unipolar EGMs were examined for positive and negative amplitude, PQ segment elevation, fractionation, and monophasic morphology. The association of these parameters with atrial capture (absence of exit block) at each site was analyzed. After achievement of entrance block, only 23 of 64 PV antra (36%) exhibited exit block. Unipolar EGMs at sites with persistent capture were more likely to be fractionated and had larger negative deflections. Bipolar EGMs at sites with persistent capture showed higher amplitude, longer duration, were more likely to be fractionated, and were less likely to be monophasic. In a multivariate logistic regression model, bipolar and unipolar fractionation, bipolar duration, and lack of bipolar monophasic morphology were independently associated with persistent atrial capture. Specific unipolar and bipolar EGM characteristics are associated with left atrium capture after PV antral isolation. These parameters might be useful in predicting the need for further ablation to achieve exit block.

Atrial Fibrillation Inducibility in the Absence of Structural Heart Disease or Clinical Atrial Fibrillation

Background— Inducibility of atrial fibrillation (AF) after pulmonary vein isolation has been used to guide additional left atrial ablation in paroxysmal AF. The sensitivity and specificity of AF induction in this setting remains uncertain. We examined the incidence and characteristics of inducible AF in patients without structural heart disease or clinical AF and the effect of different induction protocols on AF inducibility. Methods and Results— In 44 patients with supraventricular tachycardia with no history of AF or risk factors for AF, atrial refractoriness and conduction were measured, followed by AF induction attempts (10/patient). Each induction was performed after a waiting time that exceeded twice the duration of induced AF from the preceding induction. AF ≥1 minute was considered inducible, and ≥5 minutes as sustained. Burst pacing (at 200 ms for 10 seconds) was compared to decremental pacing (from 200 ms to shortest cycle length, resulting in 1:1 atrial capture for 10 seconds). After 10 inductions, AF was inducible in 49.5%, and sustained in 29.5% of patients. The incidence of both inducible and sustained AF increased with each induction. Apart from male gender, no clinical or electrophysiological features were associated with sustained AF. Decremental pacing was associated with a higher incidence of sustained AF (41.2% versus 14.8%, P =0.049), longer duration of AF ( P =0.006), and shorter mean AF cycle length ( P <0.001) compared with burst pacing. Conclusions— Inducible and sustained AF is common in patients in the absence of structural heart disease or clinical AF, and its incidence varies according to gender, method of induction, and number of inductions. There is a direct relationship between AF persistence and number of inductions, which has not reached a plateau after 10 inductions.

Kinetics of Atrial Repolarization Alternans in a Free‐Behaving Ovine Model

Kinetics of Atrial Repolarization Alternans. Repolarization alternans (Re-ALT), a beat-to-beat alternation in action potential repolarization, promotes dispersion of repolarization, wavebreaks, and reentry. Recently, Re-ALT has been shown to play an important role in the transition from rapid pacing to atrial fibrillation (AF) in humans. The detailed kinetics of atrial Re-ALT, however, has not been reported so far. We developed a chronic free-behaving ovine pacing model to study the kinetics of atrial Re-ALT as a function of pacing rate. Thirteen sheep were chronically implanted with 2 pacemakers for the recording of broadband right atrial unipolar electrograms and delivery of rapid pacing protocols. Beat-to-beat differences in the atrial T-wave apex amplitude as a measure of Re-ALT and activation time were analyzed at incremental pacing rates until the effective refractory period (ERP) defined as stable 2:1 capture. Atrial Re-ALT appeared intermittently but without periodicity, and increased in amplitude as a function of pacing rate until ERP. Intermittent 2:1 atrial capture was observed at pacing cycle lengths 40 ms above ERP, and increased in duration as a function of pacing rate. Episodes of rapid pacing-induced AF were rare, and were preceded by Re-ALT or complex oscillations of atrial repolarization, but without intermittent capture. We show in vivo that atrial Re-ALT developed and increased in magnitude with rate until stable 2:1 capture. In rare instances where capture failure did not occur, Re-ALT and complex oscillations of repolarization surged and preceded AF initiation. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1003-1012, September 2012).

Atrial Selective Effect of Amiodarone to Increase Threshold of Excitation

Increases of pacing threshold stimulation are well documented with different antiarrhythmic drugs, but not with amiodarone. We report a case of a patient with dual-chamber pacing, with stable thresholds on repeated measurements on the last year, who presented severe increase of atrial pacing threshold resulting in loss of atrial capture after a year of treatment with amiodarone. Thresholds were normalized once amiodarone was removed. Ventricular thresholds were not affected.

ORAL PRESENTATION

ORAL PRESENTATION

A Prospective Evaluation of a Protocol for Magnetic Resonance Imaging of Patients With Implanted Cardiac Devices

Magnetic resonance imaging (MRI) is avoided in most patients with implanted cardiac devices because of safety concerns. To define the safety of a protocol for MRI at the commonly used magnetic strength of 1.5 T in patients with implanted cardiac devices. Prospective nonrandomized trial. (ClinicalTrials.gov registration number: NCT01130896) SETTING: One center in the United States (94% of examinations) and one in Israel. 438 patients with devices (54% with pacemakers and 46% with defibrillators) who underwent 555 MRI studies. Pacing mode was changed to asynchronous for pacemaker-dependent patients and to demand for others. Tachyarrhythmia functions were disabled. Blood pressure, electrocardiography, oximetry, and symptoms were monitored by a nurse with experience in cardiac life support and device programming who had immediate backup from an electrophysiologist. Activation or inhibition of pacing, symptoms, and device variables. In 3 patients (0.7% [95% CI, 0% to 1.5%]), the device reverted to a transient back-up programming mode without long-term effects. Right ventricular (RV) sensing (median change, 0 mV [interquartile range {IQR}, -0.7 to 0 V]) and atrial and right and left ventricular lead impedances (median change, -2 Ω [IQR, -13 to 0 Ω], -4 Ω [IQR, -16 to 0 Ω], and -11 Ω [IQR, -40 to 0 Ω], respectively) were reduced immediately after MRI. At long-term follow-up (61% of patients), decreased RV sensing (median, 0 mV, [IQR, -1.1 to 0.3 mV]), decreased RV lead impedance (median, -3 Ω, [IQR, -29 to 15 Ω]), increased RV capture threshold (median, 0 V, IQR, [0 to 0.2 Ω]), and decreased battery voltage (median, -0.01 V, IQR, -0.04 to 0 V) were noted. The observed changes did not require device revision or reprogramming. Not all available cardiac devices have been tested. Long-term in-person or telephone follow-up was unavailable in 43 patients (10%), and some data were missing. Those with missing long-term capture threshold data had higher baseline right atrial and right ventricular capture thresholds and were more likely to have undergone thoracic imaging. Defibrillation threshold testing and random assignment to a control group were not performed. With appropriate precautions, MRI can be done safely in patients with selected cardiac devices. Because changes in device variables and programming may occur, electrophysiologic monitoring during MRI is essential.

A Surface ECG-Based Algorithm to Determine the Atrial Refractoriness of Rodents During Electrophysiological Study

Data regarding the atrial electrophysiology of rodents is hard to obtain. We hypothesized that the latency to the first R following programmed S1–S2 stimulation of the atria (defined as RRS2) is affected by atrial capture and may be utilized to determine the atrial refractoriness of rodents using a simple electrocardiogram (ECG)-based algorithm. ECG signals during programmed-stimulation protocols were evaluated in 24 anesthetized rats and 12 mice using an automated QRS detection program. In each S1–S2 stimulation the atrial capture was determined in the invasive recording and the RRS2 was determined independently in the ECG recording. Based on our hypothesis an algorithm was designed to determine atrial capture noninvasively and 95% confidence interval (95% CI) was calculated for the obtained specificity and sensitivity. In rats the ratio between RRS2 and the spontaneous RR interval (RRspon) could identify two decision-relevant ranges: RRS2/RRspon 1.113; both indicated capture of S2. In contrast, RRS2/RRspon between these values indicated failure of atrial capture. This algorithm reached sensitivity of 97.7% (95% CI 96.0–99.4%) and specificity of 96.8% (95% CI 94.8–98.8%). Following rapid atrial pacing the same algorithm reached sensitivity of 94.96% (95% CI 92.0–97.9%) and specificity of 99% (95% CI 97.7–100%). In mice, difficulties in QRS detection were encountered which somewhat limited the ECG analysis. Our results indicate that atrial electrical capture affects the latency to the first R following S1–S2 stimulation in a predictable manner. This finding may advance the ability to detect the atrial refractoriness of rodents using a simple, minimally invasive, experimental setting.

Determination of Inadvertent Atrial Capture During Para-Hisian Pacing

Inadvertent capture of the atrium will lead to spurious results during para-Hisian pacing. We sought to establish whether the stimulation-to-atrial electrogram interval at the proximal coronary sinus (stim-PCS) or high right atrium (stim-HRA) could signal inadvertent atrial capture. Para-Hisian pacing with and without intentional atrial capture was performed in 31 patients. Stim-HRA and stim-PCS intervals were measured with atrial capture, His plus para-Hisian ventricular (H+V) capture, and para-Hisian ventricular (V) capture alone. The mean stim-HRA interval was significantly shorter with atrial capture (66 ± 18 ms) than with H+V (121 ± 27 ms, P < 0.001) or V capture alone (174 ± 38 ms, P < 0.001). The mean stim-PCS interval was significantly shorter with atrial capture (51 ± 16 ms) than with H+V (92 ± 22 ms, P<0.001) or V capture alone (146 ± 33 ms, P < 0.001). A stim-PCS < 60 ms (stim-HRA < 70 ms) was observed only with atrial capture. A stim-PCS >90 ms (stim-HRA >100 ms) was observed only in the absence of atrial capture. A stim-HRA of < 85 ms was highly specific and stim-PCS of < 85 ms highly sensitive at identifying atrial capture. Stim-HRA intervals of 75 to 97 ms and stim-PCS intervals of 65 to 88 ms were observed with either atrial, His, or para-Hisian ventricular capture without atrial capture. In this overlap zone, all patients demonstrated a stim-PCS or stim-HRA interval prolongation of at least 20 ms when the catheter was advanced to avoid deliberate atrial pacing. The QRS morphology was of limited value in distinguishing atrial capture due to concurrent ventricular or H+V capture, as observed in 20 of 31 (65%) patients. Stim-PCS and stim-HRA intervals can be used to monitor for inadvertent atrial capture during para-Hisian pacing. A stim-PCS < 60 ms (or stim-HRA < 70 ms) and stim-PCS > 90 ms (or stim-HRA > 100 ms) were observed only with and without atrial capture, respectively, but there was significant overlap between these values. Deliberate atrial capture and loss of capture reliably identifies atrial capture regardless of intervals.

Failure of Atrial Capture during DDIR Pacing in a Patient with Sinus Node Disease and Preserved Atrioventricular Conduction: What Is the Mechanism?

Failure of Atrial Capture during DDIR Pacing in a Patient with Sinus Node Disease and Preserved Atrioventricular Conduction: What Is the Mechanism?

Differential Diagnosis of Supraventricular Tachycardia with Ventriculoatrial Dissociation during Ventricular Overdrive Pacing

Case Presentation A 72-year-old man with a history of multiple episodes of paroxysmal supraventricular tachycardia underwent electrophysiologic studies and a catheter ablation procedure. The 12-lead electrocardiogram during tachycardia showed long RP’ tachycardia with negative P waves in leads II, III, and aVF. Ventriculoatrial (VA) conduction with a shortest 1:1 pacing cycle length of 780 ms and earliest atrial activation at the ostium of coronary sinus was observed during ventricular overdrive pacing. A narrow QRS tachycardia documented previously was reproducibly induced by programmed atrial, though not ventricular, stimulation. During tachycardia, the His-atrial (HA) and atrial-His (AH) intervals were 381 and 156 ms, respectively. The atrial activation sequence during tachycardia seemed identical to that during ventricular pacing. A 2-mg bolus injection of adenosine triphosphate reproducibly terminated the tachycardia after a last ventricular event, following progressive prolongation of the atrial cycle length. Overdrive ventricular pacing for >30 seconds during tachycardia, at a cycle length 10‐30 ms shorter than the tachycardia cycle length, invariably caused VA dissociation without atrial capture or termination of the tachycardia (Fig. 1). What is the tachycardia mechanism? Comment

Muscle Noise Effects on Atrial Evoked Response Sensing: Implications on Atrial Auto-Threshold and Auto-Capture Determination

Automatic pacing capture verification algorithms that are based on detection of local evoked response signals are susceptible to interference from myopotential noise. This is especially true in the atrium where the lower signal amplitude and signal-to-noise ratio make pacing capture verification more challenging. The aim of this study is to evaluate the impact of myopotential noise induced by various maneuvers on the atrial evoked response (AER) signal. Data were collected from 18 patients (7 M/11 F, 77.6 ± 8.8 years), implanted with a dual chamber rate response (DDDR) pacemaker and acute and chronic right atrial leads and right ventricular leads, at three regular follow-up visits scheduled at 1, 3, and 6 months after pacemaker implantation or replacement procedures. During each study visit, manual atrial pacing threshold tests during unipolar pacing in the DDD mode were conducted with two evoked response sensing configurations (RA(Ring) → Ind and RA(Ring) → V(Tip) ) while patients performed six different maneuvers. Noise estimates were calculated for each maneuver. The greatest noise estimates in both sensing configurations were measured during the hand-pressing exercise (0.649 ± 0.342 mV in the RA(Ring) → Ind vector, 0.309 ± 0.223 mV in the RA(Ring) → V(Tip) vector). No significant differences in overall noise estimates were observed between the follow-up visits. Of the beats that exhibited noise estimates greater than a sensing floor of 0.3 mV, up to 22% of cardiac beats had a signal-to-noise ratio less than 2 in the RA(Ring) → Ind configuration. Results indicate that myopotential noise generated by performing maneuvers has a demonstrable impact on AER sensing. Therefore, noise mitigation processes are necessary in atrial automatic pacing capture verification algorithms based on evoked response signals to identify and appropriately manage noise.

204 Results of the CASA study: the automatic atrial capture management

The CASA study has included 297 patients in France implanted with an EnPulse® dual chamber pacemaker (Medtronic, Minneapolis, USA). Purpose of this study is to compare manual atrial threshold (MAT) and threshold assessed by the automatic atrial capture management function (ACM). Patients are 76 +/− 10 years old; indications were atrio-ventricular block (AVB) 70% and sinus dysfunction (SD) 30%; 31% had paroxystic atrial arrhythmias before implantation. Measurement of P wave, manual atrial threshold and atrial lead impedance have been performed at implantation, before discharge, 6 to 12 weeks after and at 6 months follow-up. At each follow-up automatic atrial thresholds are collected by interrogation of the device via telemetry and compared with the manual values by R coefficient correlation test. Follow-up (Nb) P Wave (mV) Impedance (Ohm) MAT (Volt) R coefficient ACM (Volt) Implant (297) 2.8 ± 1.6 614 ± 225 0.8 ± 0.5 Post-op (269) 2.3 ± 1.2 537 ± 153 0.7 ± 0.4 1 1 0.844 0.7 ± 0.4 1 6–12 Weeks (238) 2.3 ± 1.05 518 ± 146 0.6 ± 0.4 2 2 0.849 0.7 ± 0.4 2 6 months (186) 2.4 ± 1.2 498 ± 142 0.7 ± 0.4 3 3 0.891 0.7 ± 0.5 3 P wave amplitude and atrial lead impedance are stable during follow-up without significant difference. Concerning atrial thresholds, there is no difference between manual and automatic thresholds at each follow-up. R coefficients are very high showing an excellent correlation between the two methods. We have observed a very good correlation between atrial threshold assessed by automatic atrial capture management function and manual atrial threshold test.

Temporary neonatal atrial pacing through the umbilical venous route: A novel technique

Atrial pacing in the neonate is rarely done due to constraints of equipment, technical knowhow, and risk of complications. We describe a novel method of atrial pacing in the new born using equipment readily available in any intensive care unit. Atrial pacing can be achieved using an adult bipolar pacing wire directly introduced through the umbilical venous route. We have used this method in 5 neonates, and achieved atrial capture in 4 patients. Temporary atrial pacing is a therapeutic option in a few neonatal arrhythmias, such as atrial flutter, a few types of re-entrant tachycardias, such as accessory pathway mediated tachycardia and junctional reciprocating tachycardia, and has a limited role in cardiopulmonary resuscitation where sinoatrial node dysfunction is suspected.